1 Field of Invention
This invention relates to a particle analyzer system that analyzes elements of fine particles, for example, suspended in a clean room or contained in purified water; and more particularly, to such a system which is of reduced size and cost.
2 Description of the Prior Art
FIG. 1 shows a conventional particle component analyzer system using a microwave induced plasma, and comprising a dispersion chamber 51 in which a filter 52 is provided. Solid particles (not shown) to be measured adhere to filter 52. An aspirator 53 draws in solid particles which are stuck on filter 52 and supplies them to discharge tube 54. In dispersion chamber 51, after the air is discharged with a suction pump (not shown), helium gas is introduced and maintained at a pressure which is slightly higher than atmospheric pressure. A microwave source 55 introduces microwaves into a cavity 56.
A detection window 57 is provided at the other end of the discharge tube 54 and four optical fibers 58 introduce the beam emitted from the detection window 57 into a plurality of spectometers (four Czerny-Turner monochromators in FIG. 1) 59. The outputs of the spectrometers 59 are applied to signal processor (CPU) 60.
When the microwaves of frequency 2.45 GHz are introduced into cavity 56 from source 55, plasma at a temperature of approximately 4000 K is generated in discharge tube 54. Solid particles, which are introduced into discharge tube 54 from the dispersion chamber 51 are atomized and ionized in the plasma. The particles emit light when they fall to the ground state after further excitation. This emission spectrum is taken out from the discharge tube 54 in the axial direction and are then subjected to spectrometric analysis by spectrometers 59. Then, the output signals from the spectrometers 59 are processed by the CPU 60 to measure and display the elements contained in the samples being measured.
In addition, a photoelectric converter (not shown) is provided for each spectrometer 59 to output electrical signals corresponding to the intensity of the light beams of selected wavelengths. Amplifiers (not shown) may be provided to amplify the output signals of the photoelectric converters. The amplifiers may be provided in the latter stages of each photoelectric converter. The sizes of the particles are, for example, classified into three types, by size, such as large, medium and small, corresponding to the values of the output signals from the amplifiers. The filter 52 has a predetermined area and aspirator 53 scans the filter 52 a plurality of times to draw in the same quantity of particles with each scan.
FIG. 2 shows the relationship between the emission wavelengths of the elements and the emission intensities and in practice about 50 elements are the object of the measurement. As seen in FIG. 2, for example, manganese (Mn) has an emission wavelength near 2600 Angstrom, and Aluminum (Al), fluorine (F), and oxygen (O) have emission wavelengths near 3950, 6900, and 7800 Angstrom, respectively.
Since photo emission is introduced into a plurality of spectrometers (e.g. four spectrometers) whose measuring wavelengths are fixed, only four components can be captured in one emission. Because the particles may contain a number of various elements, such as described above, the measurement may have to be carried out a plurality of times with the wavelength settings of the spectrometers being changed for each measurement. Thus, measurement with prior art devices takes a long time. Although the problem may be solved with use of a larger number of spectrometers to shorten the measuring time, this requires a very large system, and also increases the cost of such system,since spectrometers are expensive.